There are about 2000 pulsars known, and while all of them as neutron
stars are fascinating objects, the best and most exciting science comes
from a very small percentage (~1%) of exotic objects, most of which are
millisecond pulsars (MSPs). These systems are notoriously hard to
detect, yet their numbers have more than doubled in the past 5-6 years
via surveys using the world's largest radio telescopes and the Fermi
Gamma-ray Space Telescope. Timing observations of these new MSPs as
well as much improved monitoring of previously known MSPs are providing
a wealth of science. In this talk I'll cover 3 main areas in basic
physics where systems like these are making an impact: strong-field
tests of general relativity, the nature of matter at supra-nuclear
densities (including the recent accurate measurement of a two Solar mass
neutron star), and the direct detection of gravitational waves
(e.g. NANOGrav) likely within the next decade.